This test uses self._create_server to create VMs instead of
self._create_vms_by_topology, which is the method used by most of other
QoS tests.
self._create_vms_by_topology deploys two servers on different computes
by default, using scheduler_hints. This patch adds required scheduler_hints
value to guarantee VMs created by
test_attach_qos_port_to_vm_with_another_port are spawned on different
computes too.
Change-Id: Iefd0c8c06b2e1e84c0972049882546e11ee10897
e67f790479